1. Field of the Invention
Embodiments of the present invention relate to a semiconductor substrate processing system. More particularly, embodiments of the invention relate to a gas flow diffuser for controlling the flow of gases within a semiconductor substrate processing chamber.
2. Background of the Related Art
Integrated circuits have evolved into complex devices that can include millions of components (e.g., transistors, capacitors, resistors, and the like) on a single chip. The evolution of chip designs continually requires faster circuitry and greater circuit density. The demands for greater circuit density necessitate a reduction in the dimensions of the integrated circuit components. The minimal dimensions of features of such devices are commonly referred to in the art as critical dimensions. The critical dimensions generally include the minimal widths of the features, such as lines, columns, openings, spaces between the lines, and the like.
As these critical dimensions shrink, process uniformity across the substrate becomes paramount to maintain high yields. One problem associated with a conventional plasma etch process used in the manufacture of integrated circuits is the non-uniformity of the etch rate across the substrate, which may be due, in part, to a lateral offset between the reactive species and the substrate being etched. One factor contributing to the tendency of the reactive species to be offset from the center of the substrate is the radial location of the chamber exhaust port. As gases are more easily pumped from areas of the chamber that are closest to the exhaust port, the reactive species are pulled toward the exhaust port, thereby becoming offset with respect to the center of the chamber and the substrate positioned therein. This offset contributes to a loss of etch uniformity over the surface of the substrate which may significantly affect performance and increase the cost of fabricating integrated circuits.
A flow restricting device may be positioned within the chamber to change the chambers conductance in order to compensate for the offset of the pumping port. Although this technique has demonstrated good processing results, a level of process uniformity has not been achieved that will enable next generation devices, believed at least in part to be due to the inability to completely compensate for conductance non-uniformity above the substrate being processed within the processing chamber. Thus, as linewidths and critical dimensions continue to shrink, the need remains for a continued improvement in process uniformity in order to enable fabrication of next generation devices at a practical cost of manufacture.
Therefore, there is a need in the art for an improved apparatus for etching material layers during the manufacture of integrated circuits.